1. Field of the Invention
The present invention relates to a manufacturing technique capable of manufacturing a product in which a component having a predetermined length and made of a shape memory alloy is provided so as to be stretched.
2. Description of the Background Art
There is an actuator using the characteristics of a shape memory alloy (SMA) which regains its original shape when heated. As an example of the actuator using the SMA, there is an actuator which can operate by expansion and contraction of an SMA wire provided so as to be stretched.
The SMA wire has, however, the characteristic that it stretches in a stress application direction in a state where the elastic coefficient (elasticity value) is low. Consequently, at the time of stretching the SMA wire in assembly of an actuator, unintentional stretch occurs in the stress application direction. Since variations occur in the initial stretch or the displacement of the SMA wire at the time of heating in the actuator assembled in such a manner, there is a problem such that the quality of the actuator (product) deteriorates.
For example, in the case where an SMA wire 90 is fixed to a fixing part 92, fed from a guide 91, and stretched as shown in FIG. 18, if the guide 91 is moved in a direction of loosening the SMA 90 (the minus lead direction), the SMA 90 contracts. It causes torsion and hinders assembly of the actuator.